MT9044 Mitel Networks Corporation, MT9044 Datasheet - Page 7

• Manufacturer Part Number: MT9044
• Description: T1/E1/OC3 System Synchronizer
• Manufacturer: Mitel Networks Corporation

Advance Information
In Normal Mode, the DCO provides an output signal
which is frequency and phase locked to the selected
input reference signal.
In Holdover Mode, the DCO is free running at a
frequency equal to the last (less 30ms to 60ms)
frequency the DCO was generating while in Normal
Mode.
In Freerun Mode, the DCO is free running with an
accuracy equal to the accuracy of the OSCi 20MHz
source.
Output Interface Circuit
The output of the DCO (DPLL) is used by the Output
Interface Circuit to provide the output signals shown
in Figure 5. The Output Interface Circuit uses four
Tapped Delay Lines followed by a T1 Divider Circuit ,
an E1 Divider Circuit, a DS2 Divider Circuit and an
analog PLL to generate the required output signals.
Four tapped delay lines are used to generate a
16.384MHz, 12.352MHz, 12.624MHz and 19.44 MHz
signals.
The E1 Divider Circuit uses the 16.384MHz signal to
generate four clock outputs and three frame pulse
outputs.
generated by simply dividing the C16o clock by two,
four and eight respectively. These outputs have a
nominal 50% duty cycle.
The T1 Divider Circuit uses the 12.384MHz signal to
generate two clock outputs.
generated by dividing the internal C12 clock by four
and eight respectively.
nominal 50% duty cycle.
The DS2 Divider Circuit uses the 12.624 MHz signal
to generate the clock output C6o. This output has a
nominal 50% duty cycle.
The C8o, C4o and C2o clocks are
These outputs have a
C1.5o and C3o are
The frame pulse outputs (F0o, F8o, F16o, TSP, RSP)
are generated directly from the C16 clock.
The T1 and E1 signals are generated from a
common DPLL signal.
outputs C1.5o, C3o, C2o, C4o, C8o, C16o, F0o, F16o
and C6o are locked to one another for all operating
states, and are also locked to the selected input
reference in Normal Mode. See Figures 20 and 21.
All frame pulse and clock outputs have limited driving
capability, and should be buffered when driving high
capacitance (e.g. 30pF) loads.
Analog Phase Lock Loop (APLL)
The analog PLL is intended to be used to achieve a
50% duty cycle output clock. Connecting C19o to
ACKi will generate a phase locked 19.44 MHz ACKo
output with a nominal 50% duty cycle. The analog
PLL has an intrinsic jitter of less than 0.01 U.I. In
order to achieve this low jitter level a separate pin is
provided to power (AVdd) the analog PLL.
DPLL
From
ACKi
Figure 5 - Output Interface Circuit Block
Tapped
Tapped
Tapped
Tapped
Delay
Delay
Delay
Delay
Line
Line
Line
Line
12MHz
16MHz
19MHz
12MHz
Diagram
Consequently, the clock
Analog PLL
DS2 Divider
T1 Divider
E1 Divider
MT9044
C19o
C1.5o
C3o
C2o
C4o
C8o
C16o
F0o
F8o
F16o
ACKo
C6o
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